Organic EL display device and method for fabricating the same

ABSTRACT

An organic EL display device and a method for fabricating the same are disclosed, wherein an organic luminescence layer is formed at a crossing region of first and second electrodes using a shadow mask on which a plurality of holes are connected by bridges.

[0001] This application claims the benefit of the Korean Application No.2001-0039542 filed on Jul. 3, 2001, which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a display device, and moreparticularly, to an organic electroluminescence(EL) display device and amethod for fabricating the same.

[0004] 2. Discussion of the Related Art

[0005] A method of using a shadow mask as shown in FIG. 1 is the mostefficient method to improve the luminescence efficiency among methods offorming R, G, and B pixels in fabricating a full-color organic ELdisplay device.

[0006]FIGS. 1A to 1D are diagrams showing a related art shadow mask anda full-color organic EL display device according to a pixel arraymethod.

[0007] As shown in FIG. 1A, an first electrode 2 is formed on atransparent substrate 1 and barriers 7 are additionally formed on thesame to separate between an insulating film 3 and a second electrode

[0008] Also, using a shadow mask 6, a common luminescence layer 5 of R,G, and B, and each of organic luminescence layers 5-1 to 5-3 of R, G,and B is formed at a corresponding pixel on the insulating film 3.

[0009] Then, the second elecrode is formed on the entire surface.

[0010] There are three different types(i.e. a strip type as shown inFIG. 1B, a delta type as shown in FIG. 1C, and an array type as shown inFIG. 1D) in forming an organic luminescence layer using a shadow maskdepending on the array method of a pixel. In the array type, the size ofR pixel is designed to be larger than G or B pixel to supplement theluminescence efficiency of the R pixel.

[0011] The strip type is best among the above three pixel array types interms of the aperture ratio and first electrode resistance. In otherwords, because first electrodes are formed in the form of strips, thedevice can be driven with low driving voltage.

[0012] On the other hand, in the strip type, the shadow mask 6 shouldalso be made in a strip form as shown in FIG. 1. In this instance,problems such as the transformation or droop of the shadow mask 6 arecaused in a large degree because of an external pulling strength.Accordingly, in the process of deposition, colors spread not only on theintended pixel region but also on other areas because of shadow effect.

[0013] To obviate the above-mentioned problems, as shown in FIG. 2, ashadow mask on which mask holes are made in turns while having the samepixel array structure as that of the strip type of FIG. 1B is applied.

[0014]FIGS. 2A to 2D are deposition process diagrams of an organicluminescence layer of a full-color organic EL display device using therelated art shadow mask structure.

[0015] In this method, however, each organic luminescence layerdisplaying one of R,G,and B colors should be formed by carrying outalignment and deposition twice respectively. That is, to form threelayers of R,G,and B, the deposition should be carried out six times inall after the alignment being carried out six times as well.

[0016] In other words, to form organic luminescence layers of R, G, andB, in case of using the shadow mask 6 of FIGS. 1B to 1D, the shadow maskis aligned and deposited three times respectively. In case of using ashadow mask shown in FIG. 2, however, the shadow mask should bedeposited 6 times.

SUMMARY OF THE INVENTION

[0017] Accordingly, the present invention is directed to an organic ELdisplay device and method for fabricating the same that substantiallyobviates one or more problems due to limitations and disadvantages ofthe related art.

[0018] An object of the present invention is to provide a full-colororganic EL display device and a method for fabricating the same, inwhich an improved shadow mask structure is provided to prevent a maskpattern from being transformed, thereby obtaining high luminescenceefficiency.

[0019] Another object of the present invention is to provide afull-color organic EL display device and a method for fabricating thesame which has a shadow mask structure that provides a predeterminednumber of bridges formed over a long strip-shaped holes so as to preventtransformation and droop caused by a pulling strength from occurring,thereby obtaining high aperture ratio and low driving voltage.

[0020] Additional advantages, objects, and features of the inventionwill be set forth in part in the description which follows and in partwill become apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

[0021] To achieve these objects and other advantages and in accordancewith the purpose of the invention, as embodied and broadly describedherein, a full-color organic EL display device of the present inventionincludes organic luminescence layers of R,G,and B formed in a stripshape at a plurality of pixels, which are defined by a crossing regionof first and second electrodes, on a transparent substrate using a maskwhich has a plurality of strip-shaped holes and a plurality of bridgescrossing the holes.

[0022] In the preferred embodiment of the present invention, thin metalthat act as bridges is formed over long strip-shaped holes of a shadowmask so as to prevent the shadow mask from being transformed or droopedbecause of the pulling strength. The organic luminescence layers ofR,G,and B are alternately arranged in rows by three times' alignments ofthe shadow mask.

[0023] It is to be understood that both the foregoing generaldescription and the following detailed description of the presentinvention are exemplary and explanatory and are intended to providefurther explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of this application, illustrate embodiment(s) of theinvention and together with the description serve to explain theprinciple of the invention. In the drawings:

[0025]FIGS. 1A to 1D illustrate diagrams showing full-color organic ELdisplay devices in accordance with pixel array types and related artshadow masks;

[0026]FIGS. 2A to 2D illustrate deposition process diagrams of anorganic luminescence layer of a full-color organic EL display deviceusing a shadow mask structure of a related art;

[0027]FIGS. 3A to 3D illustrate deposition process diagrams of anorganic luminescence layer of a full-color organic EL display deviceusing a shadow mask structure of the present invention;

[0028]FIG. 4 illustrates a plane view of a shadow mask in accordancewith the present invention; and

[0029]FIGS. 5A to 5C are detailed diagrams showing a part ‘A’ of theshadow mask of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

[0030] Reference will now be made in detail to the preferred embodimentsof the present invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

[0031]FIGS. 3A to 3D illustrate deposition process diagrams of anorganic luminescence layer of a full-color organic EL display deviceusing a shadow mask structure of the present invention.

[0032] Referring to FIG. 3A, a first electrode 20 of a transparentelectrode material is formed on a transparent substrate 10. Asupplementary electrode may be applied to reduce the resistance of thefirst electrode 20. The substrate includes at least thin filmtransistors.

[0033] Metals which have relatively lower resistance than the resistanceof the first electrode 20, such as Cr, Al, Cu, W, Au, Ni, and Ag, can beused as the supplementary electrode.

[0034] An insulating film 30 is formed on the first electrode 20. Anyinsulators, regardless of inorganic materials or organic materials, canbe used as the insulating film 30.

[0035] A barrier 70 is formed on the insulating film 30 to insulateintervals of each second electrode(not shown).

[0036] As shown in FIG. 4, a shadow mask 60 is used to form each organicluminescence layer of R,G,and B and a common organic luminescence layerof the same at a plurality of pixels on the transparent substrate 10.The pixels are defined by a region crossed by the first and secondelectrodes.

[0037]FIG. 4 is a plane view of the shadow mask 60 in accordance of thepresent invention. The shadow mask 60 has a plurality of strip-shapedholes and a plurality of bridges 60-1 which connect the holes.

[0038] The transformation of the shadow mask 60 is prevented by thebridges 60-1 which connect the holes.

[0039] Referring to FIG. 3A, one bridge 60-1 for each pixel is formed,but the bridge 60-1 is not necessarily formed at every pixel. Inconsideration of the transformation of the shadow mask 60, the bridgemay be formed between every two or three pixels.

[0040] Preferably, the bridge 60-1 has its width ‘a’ and thickness ‘b’in the range of 1˜1000 μm.

[0041]FIGS. 5A to 5C illustrate a detailed view of the part ‘A’ of theshadow mask of FIG. 4. The bridge 60-1 can be formed either on the sameplane and at the same thickness as the shadow mask 60 as shown in FIG.5A, or on a different plane and at a different thickness from the shadowmask 60 as shown in FIG. 5B. Alternatively, the bridge 60-1 can also beformed on the same or different plane as or from the shadow mask at adifferent thickness from the shadow mask 60 as shown in FIG. 5C.

[0042] A common luminescence layer of R, G, and B (not shown) isdeposited on the transparent substrate 10 at a time using a blank maskwhich can deposit all the entire luminescence region.

[0043] Subsequently, each organic luminescence layer of R, G, and B isalternately arranged in rows at the pixel by three times aligning theshadow mask 60.

[0044] The common luminescence layer of R, G, and B may also be formedat each pixel of R, G, and B using the shadow mask 60, not beingdeposited on the entire luminescence region.

[0045] Subsequently, the second electrode (not shown) is formed byforming a second electrode (Mg—Ag alloy, or Al, or other conductivematerials) using the blank shadow mask.

[0046] Then, passivation layers(oxygen adsorption layer, moistureadsorption layer, and moisture-proof layer) are formed on the secondelectrode and encapsulation is carried out.

[0047] The full-color organic EL display device in accordance with thepresent invention has the following advantages.

[0048] By forming mask holes in the form of a bridge, the transformationand droop of the shadow mask caused by the pulling strength isprevented. Thus, efficiency of the full-color organic EL display deviceis maximized.

[0049] It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present invention. Thus,it is intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. An organic EL display device comprising: a substrate; a first electrode formed on the substrate; an organic luminescence layer formed on the first electrode; and a second electrode formed on the organic luminescence layer, wherein the organic luminescence layer is formed using a mask on which a plurality of holes are connected by bridges.
 2. The organic EL display device of claim 1, wherein the bridges are formed on the same plane and at the same thickness as the mask.
 3. The organic EL display device of claim 1, wherein the bridges are formed on a different plane and at a different thickness from that of the mask.
 4. The organic EL display device of claim 1, wherein the bridges are formed on the same or different plane as or from the mask and at a different thickness from that of the mask.
 5. The organic EL display device of claim 1, wherein the bridges have their width and thickness in the range of 1-1000 μm.
 6. The organic EL display device of claim 1, wherein the bridges are formed of thin metal.
 7. The organic EL display device of claim 1, wherein the holes have a strip shape.
 8. The organic EL display device of claim 1, wherein the organic luminescence layer has either each organic luminescence layer of R,G,and B and a common organic luminescence layer of the same, or each luminescence layer of R,G,and B and common organic luminescence layers which are formed on each luminescence layer of R,G,and B.
 9. A method for fabricating a display device comprising steps of: forming a first electrode pattern on a substrate; forming at least one organic luminescence layer having a plurality of holes by aligning a mask having a plurality of bridges that connect the holes; and forming a second electrode pattern on the organic luminescence layer in a perpendicular direction to the first electrode.
 10. The method of claim 9, wherein the mask is aligned three times so that each organic luminescence layer of R,G,and B is alternatively arranged in a row direction.
 11. The method of claim 9, wherein the substrate includes at least thin film transistors. 